In a high pressure nitration process, a hydrocarbon, such as propane, and an organic acid, such as acetic acid, propanoic acid, and/or butanoic acid, reacts with aqueous nitric acid to yield products such as nitromethane, 1-nitropropane, and 2-nitropropane. In addition, the process produces a significant amount of water and some organic acids. Many of the organic acids fed to the reactor are not converted in a single pass through the reactor. Thus, in order to recycle the organic acids back to the reactor, much of the water needs to be removed. Because the relative volatility between acetic acid and water is low, conventional distillation is energy-consuming and costly. In addition, propionic and n-butanoic acid form low-boiling azeotropes with water, resulting in unavoidable acid losses in the distillation overhead if conventional distillation is used. Alkyl acetates may be used as entrainers for azeotropically removing water from an aqueous organic acid stream. However, because the recovered organic acid is recycled back to the reactor, the presence of alkyl acetates in the organic acid stream could pose potential problems. A need exists, therefore, for more economical and energy efficient processes and apparatuses for the removal of water from organic acid streams. A need also exists for processes and apparatuses to recover an organic acid stream that can be recycled for use in a high pressure nitration process without additional purification.